This application relates to digital image processing techniques.
The present invention relates to video coding techniques. Video distribution systems include a video source and at least one receiving device. The video content may be distributed over a network or over fixed media. To keep complexity and cost low, video content is typically limited in dynamic range, e.g., 8-10 bit signal representations and 4:2:0 color format. Recent advances in display technology, however, have opened the door for the use of more sophisticated content (also referred to as higher quality content), including content characterized as High Dynamic Range (HDR) and/or wide color gamut (WCG), as well as content with increased spatial and/or temporal resolution. This higher quality content is typically converted to a lower range using a Transfer Function (TF) that is followed by a quantization to a particular fixed bit-depth precision (e.g. 8 or 10 bits). The conversion may also include a color space conversion process, in a space that may be friendlier for encoding, as well as color format conversion, e.g. converting data from 4:4:4 or 4:2:2 to a representation with fewer chroma samples (e.g. 4:2:2 and 4:2:0), before encoding for distribution using a video compression system. These steps can introduce banding and other artifacts that may impact and substantially degrade the quality of the video content when decoded and displayed.